A/C blowing in defrost mode!

[C man]

Lately my a/c has been acting funny. Last week it would all of a sudden start to blow in defrost mode. At first I thought the climate control was malfunctioning becuse it would be fine if I restarted the car. It only happened twice

But today it did the same thing three times. I remembered that this is defualt mode for cars when there is a vaccum leak. I assume that what it is becuase it worked fine on the interstate and only went in defualt mode in stop in go traffic and when I accelerated a little hard.

My ? is, Should I replace the vaccum line that connects from the intake manifold to the the fire wall. What I really asking is were is the vaccum line for the HVAC located at.

[C man]

Ok maybe it the climate control unit. It flashing celius temp, then it flashes in regular temp back in forth and the it just goes in default mode.

Is this the climate control unit on its way out?

[imidazol97]

Originally Posted by C man

Ok maybe it the climate control unit. It flashing celius temp, then it flashes in regular temp back in forth and the it just goes in default mode.

Is this the climate control unit on its way out?

If it's the vacuum lines on the motor or at the storage tank, it usually would stay in defrost. The lines tend to rot and dry. They crack and leak. Then if yours is still vacuum operated motors for the air flow doors, the connector on the programmer for the vacuum lines can suck closed.

But your problem sounds more like electrical problems. The busses for grounds are under the door sills on leSabres and are the same on Park Avenues I assume. Cars with water problems or living in wet areas where carpet can stay wet would be most likely to corrode.

http://i86.photobucket.com/albums/k1...7/100_1930.jpg

[ZiggyPA]

Have you tried the diagnostic mode? I had a thread about that about a month ago, but am not sure the procedure would be the same on a 95.

[imidazol97]

Originally Posted by ZiggyPA

Have you tried the diagnostic mode? I had a thread about that about a month ago, but am not sure the procedure would be the same on a 95.

I believe that diagnostic mode was last on the 93 or 94. I suspect 93 was the last year. People talk about 94 and 95 being the OBC 1.5 problem for connecting to the ALDC.

One thiing the poster might check is after figuring out where the ground buss is, try hitting that area with his heel to vibrate the connector hoping that if it is a ground not quite connecting vibration will remake the connection. And that buss (and the one on the passenger side) may not be involved. I know my 93 leSabre had power door locks and AC control that would occasionally quit for a few minutes or until the car sat; the AC defaulted to defrost with the compressor and fans on.

[C man]

I don't live in a wet or salty area. I think I know the ground bus connection you mentioned. None of the other symptoms associated with it are happening though. Everything else works just fine. But the display does start to act crazy like half display the temp and fan speed before it act up or it will just come on by itself so it could be a very well be an electrical problem.
I went to the parts department at the dealership and he said that the had been selling a lot of actuators since summer has came so I'll try testing this next. If I find the solution I'll post. I hope its a cheap fix whatever the problem is. =

[C man]

Pretty sure I found the soulution to my problem. I think one of the vaccum lines for one of the actuators was lose. Which caused a slow vaccum leak. I observed the door for recirculation slowly close with the ignition key on in a/c mode. Which it shouldn't do with max a/c on.

So I just pushed all the vaccum lines tight on the actuators and I haven't had a problem since. I guess the system went haywire when the vaccum was lost. Doesn't make since to me as to why the climate control would display eratically though. I also made sure the hvac control box connection was secure. Save myself a lot of headache. So im happy

[C man]

I really solved the problem! Turns out the climat control unit was going bad. It finally started blacking out. Went to the dealership for a price qoute they said $921!! which is crazy. How does gm plan to stay in business this way?

Anyway I went to the junkyard and most of the climate control units were gone or not compatabile. Well on my way out I spotted 2 98' park avenues and one of them had the climate control unit. I got it and the price $12.

I ended up have to exchange the mounting bracket/face out so it could fit and mount in the dash, and some buttons from the newer one . While I had the unit apart I notice that the iternals were diffrent somewhat hopefully a design upgrade since 98' was the last year for that climate control. I'm happy again for only $12 and it looks almost new.

[HotZ28]

Went to the dealership for a price qoute they said $921!! which is crazy. How does gm plan to stay in business this way?

That is exactly how GM plans to stay in business, charge enormous prices for parts and eliminate 1000 dealers, in an effort to eliminate competition on pricing. BTW, good find at the JY, does the 98 unit have a recirculate button; and if so does it work?

[C man]

The 98' climate control was exacly the same externally except the fact that the face had the screw brackets mounted on the side instead of the top like I would assume for the 91-96' models. So I had to to take the face off mine which included all the buttons and put it on but I used the auto and off buttons from the new jy unit because mine was worn pretty bad. I haven't used the recirculate button yet but will try today. Thw only diffrence I noticed inside was that the old unit had to things labled IRC (don't know a lot about electronics) and the newer model used what appeard to be 3 very big gray resistores in the 2 IRC's place. They're probly not resistores since they are not colored coded but the look like them Should have took pics.

That is exactly how GM plans to stay in business, charge enormous prices for parts and eliminate 1000 dealers, in an effort to eliminate competition on pricing.

That seems to give them the potential to lose more customers. I have family members that have newer GM cars, they are pretty good but price qoutes like that make me reconsider getting a new GM car when I can afford one.